1. Field of the Invention
The present invention generally relates to sealed oxygen containers and, more particularly, is concerned with oxygen containers that are weldably sealed and may be readily opened for quick discharge of the contained gas.
2. Brief Description of the Prior Art
Generally speaking, cylinders containing compressed gases are well-known. Compressed gases can be stored in large cylinders and dispensed with valves and regulators. Large cylinders of the type used for welding are refilled through open necks that are provided with mechanical closure devices. Such cylinders usually contain compressed gases of the type including carbon dioxide, methane, nitrogen, and oxygen.
In addition to the aforementioned large cylinders generally used for commercial or industrial applications, smaller compressed gas cylinders have wide applicability. Such uses include containment of nitrous oxide for whipping cream, nitrogen for low temperature applications, carbon dioxide for carbonated beverages and dry ice formation, among others, but not containment of oxygen. These small cylinders are usually sealed by mechanical crimping or pressure welding a closure cap onto the cylinder filling neck. There are usually no adverse reactions that could result from these sealing procedures.
However, a very definite need exists in many applications for small, that is approximately 10-30 grams, oxygen cylinders which could be used to inflate life jackets, safety hoods for fire fighters, smoke hoods for immediate breathing sources for people trapped in a confined area wherein a fire may occur, such as in an airplane, or for use by miners working in an environment containing contaminated gases.
Sealing small oxygen cylinders presents several problems. First, the pressure of the contained gas is usually so high, as in the order of approximately 3,000 psi, that a mechanical seal such as a crimped closure cap is not satisfactory. Even if a crimped cap could be successfully inserted and held within the cylinder filling neck, oxygen will gradually start to leak out within a relatively short period of time. This deficiency is clearly shown in U.S. Pat. No. 2,685,383 issued to W.B. Kochner. In this patent, a pressure bulb cap is welded onto the neck of a pressure bulb that contains carbon dioxide. The technique disclosed by Kochner would not be suitable for pressure bulbs that may be charged with oxygen contained under high presure. The oxygen would leak out through the filling neck and remain in the vicinity where welding would occur. The likely occurrence of an explosion is readily apparent.
The most suitable procedure for sealing small cylinders filled with oxygen would be providing a barrier within the cylinder filling neck so that oxygen could not escape from the cylinder thereby allowing a closure cap to be heat welded onto the filling neck without damage. Presently, there does not appear to be a procedure whereby oxygen can be contained within the cylinder and not leak into the atmosphere adjacent to the area where the closure cap would be heat welded. The heat generated by electric fusion welding in combination with oxygen in the immediate vicinity of the cylinder filling neck is likely to create a potential for a highly explosive environment.
Thus, the advantages offered by, and the need for, small oxygen-filled cylinders is apparent. This need will become more acute as, for example, solutions to get passengers off burning airplanes, providing safety hoods for fire fighters and miners obtains more recognition by public and private agencies. A need exists for oxygen-containing cylinders that can be rendered safe to allow a closure cap to be heat welded thereon.